N-phenylbenzamide derivatives

ABSTRACT

N-phenylbenzamide derivatives of the general formula I ##STR1## wherein the radicals R 1 , R 2 , and R 3 , which can be the same or different, are a hydrogen atom or a methyl radical, as well as the pharmacologically acceptable salts thereof for controlling malignant, proliferative and auto-immune diseases and for immunosuppressive therapy upon grafting are described.

BACKGROUND OF THE INVENTION

Diaminobenzanilide derivatives have become known as starting productsfor the manufacture of polyurethane elastomers from U.S. Pat. No.3,926,922. Nevertheless, no pharmacological properties have beendescribed for this class of compounds.

SUMMARY OF THE INVENTION

The present invention relates to compounds of the general formula I##STR2## wherein the radicals R¹, R², and R³, which can be the same ordifferent, are a hydrogen atom or a methyl radical, as well as thepharmacologically acceptable acid addition salts thereof, possessinteresting pharmacological properties, which make them suitable inparticular for the treatment of malignant, proliferative and auto-immunediseases as well as for immunosuppressive therapy with transplantations.

Those compounds of the general formula I, wherein radicals R¹ and R²possess at least one methyl radical, are new compounds, which arecharacterized by the following general formula II: ##STR3## wherein atleast one of the radicals R⁴ and R⁵ represents a methyl radical, and theremaining radicals R⁴ to R⁶, which can be the same or different, are ahydrogen atom or a methyl radical.

Thus, the present invention is concerned with new compounds of thegeneral formula II, as well as with the application of compounds of thegeneral formula I and pharmaceutical compositions thereof for thetreatment of diseases of the immune system and for immunosuppressivetherapy.

DETAILED DESCRIPTION

The compounds of the general formula II may be prepared by reacting,with one another in a previously known manner, compounds of the generalformula IIIa and b: ##STR4## wherein A is a reactive acid group, Z ahydrogen atom or a methyl group and X and Y, which can be the same ordifferent, are an amino group provided with a protective group or anitro group, the compounds thus obtained of the general formula IV,##STR5## wherein X, Y, and Z have the aforementioned meanings, arereacted with hydrogen, and, if desired, subsequently converted by meansof acids into the pharmacologically acceptable salts thereof.

Compounds of the general formulas I and II are particularly preferred,wherein the radicals --NH--R¹ and NH--R⁴ are in para position to thecarbonyl group.

The following individual substances are particularly preferred on thebasis of their pharmacological action:

4-Amino-N-(2'-aminophenyl)-benzamide

4-methylamino-N-(2'-aminophenyl)-benzamide

4-amino-N-(2'-methylaminophenyl)-benzamide

4-amino-N-(2'-aminophenyl)-N-methyl-benzamide

As salts, included are all therapeutically acceptable acid-additionsalts, e.g. salts with hydrohalogenides, such as hydrochloric acid orhydrobromic acid, sulfuric acids, phosphoric acids, nitric acid,aliphatic, alicyclic, aromatic or heterocyclic carboxylic or sulfonicacids, such as formic acid, acetic acid, propionic acid, succinic acid,glycolic acid, lactic acid, malic acid, tartaric acid, citric acid,ascorbic acid, maleic acid, hydroxymaleic acid or pyruvic acid;phenylacetic acid, benzoic acid, p-aminopenzoic acid, anthranilic acid,p-hydroxybenzoic acid, salicylic acid or p-aminosalicylic acid,methanesulfonic acid, ethanesulfonic acid, hydroxyethanesulfonic acid,ethylenesulfonic acid; halogen benzenesulfonic acid, toluenesulfonicacid, naphthalenesulfonic acid, or sulfanilic acid; methionine,tryptophan, lysine or arginine.

The active substances according to the invention are advantageouslyadministered in the form of a pharmaceutical preparation, which containsthe active substances in free form or in the form of one of theirtherapeutically acceptable salts, mixed with pharmaceutical organic orinorganic solid or liquid carriers suitable, for example, for topical,enteral, e.g. oral or rectal, or above all, parenteral, such as IM or IVapplication. Those substances can be considered for the formationthereof which do not react with the new compounds, for example gelatine,lactose, starch, stearyl alcohol, magnesium stearate, talc, vegetableoils, benzyl alcohols, propylene glycols, vaseline or otherpharmaceutical carriers.

The pharmaceutical preparations can be in the form of e.g. tablets,sugar-coated tablets, capsules, suppositories, ointments, creams or inliquid form as solutions, suspensions or emulsions. If necessary, theyare sterilized and/or contain adjuvants such as preserving, stabilizing,wetting or emulsifying agents, solutes or salts to change the osmoticpressure or buffers. They can also contain further active substances.

The dosage to be applied depends on the clinical picture of the diseaseto be treated and on individual factors.

Doses of 10 to 300 mg, in particular 20 to 100 mg are generallyadministered. The individual dosage can also exceed this in specialcases.

The compounds according to formula IIIa are reacted with compounds offormula IIIb in a previously known manner. Particularly acidhalogenides, acid anhydrides or acid imidazolides or ester groups areused as reactive acid groups A, these permitting a reaction with theamino group. Thus, A denotes preferably halogen, imidazolyl, acyl orlower alkanoyl groups.

The usual groups which are also found in peptide chemistry, e.g. theacetyl, the benzyloxy or the carbobenzoxy group may be used asprotective groups for X and/or Y.

The reaction with hydrogen using suitable catalysts (platinum orpalladium) is conducted in such a manner that on the one hand the freenitro groups are reduced to primary amino groups and, on the other hand,the protective groups attached to the amino groups are split offhydrogenolytically. In this manner one arrives at the methyl-substitutedor unsubstituted amino groups R¹ --NH--, R² --NH-- or R⁴ --NH--, and R⁵--NH--, as desired. An acetyl group being used as protective group issplit off hydrolytically e.g. with hydrochloric acid.

The substances according to the invention possess surprisingpharmacological activities and are in particular agents forimmunosuppression/immunoregulation in skin, organ and bone marrowtransplantations, for immunosuppression/immunoregulation in disturbancesof the cellular and humoral immune system (e.g. autoaggression diseases,immuno-complex diseases, diseases of rheumatic typology), for topicaland/or systemic treatment of malignant neoplasia (including those of thehematopoietic system, the skin, CNS) and for the topical and/or systemictreatment of benign proliferative diseases (e.g. psoriasis). On thebasis of the proven cytostatic action an antiviral action is also takeninto consideration.

The compounds of the general formula I can be distinguished from theknown cytostatic and immunosuppressive agents particularly on account oftheir lipophilia, inherent in their chemical structure, by theirpotency, their topical activity and the controlability of their actionand side-effects due to special kinetics of action.

Contrary to most substances, which cannot pass the blood-drain barrierdue to their hydrophilic properties and therefore do not allow asatisfactory therapeutical influence e.g. on malignant tumors of theCNS, the substances according to the invention reach the CNS as aconsequence of their favoring distribution coefficient (log V_(K) ofexample 1=2.2, n-octanol/water pH 7.4/20° C.). This is also the casewith intragastric application, as shown by certain pharmacologicaleffects.

The passing of the blood-brain barrier has opened up new avenuespreviously unknown for influencing therapeutically proliferative as wellas auto-immune processes in the CNS. With a lipophilic cytostatic agentthere is still the possibility of enrichment in particularly high-fattumors, whereby a more efficient medicinal influence on such neoplasmscan be achieved.

Comparison investigations of the substances according to the inventionagainst the immunosuppressive standard azathioprine demonstrate theformers' superiority: to obtain approximately the same effect on thesurvival time of allogeneic skin grafts in rats, 300% to 700% higherdoses are necessary in the case of azathioprine compared to thecompounds of formula I.

No report has yet been presented for traditional cytostatic agents on atopical antiproliferative activity, as can be demonstrated for thesubstances according to the invention.

Furthermore, it was found that the suppressive action on peripheralleukocytes and lymphocytes in rhesus monkeys is quickly reversible upondiscontinuing one of the substances according to the invention. Nocomparable short-term extensive reattainment of normal hematologicalfindings can be observed with the conventional cytostatics andimmunosuppressive agents (e.g. cyclophosphamide, methotrexate,azathioprine). It can be concluded from this that overdoses arising fromindividually varying responses and the resulting side-effects are betterto control than with conventional cytostatics and immunosuppressiveagents.

Steroids, azathioprine, antilymphocyte globulin (ALG), antithymocyteglobulin (ATG) and cyclosporine A are used in immunosuppression. Theside-effects of these therapies are considerable, and the complicationsdangerous. The compounds of the present invention demonstrate aparticular lack of side-effect and purely for this reason alonerepresent great therapeutic progress.

The current psoriasis medication has to be designated as extraordinarilyunsatisfactory. Corticoids are amongst the most effective antipsoriaticagents. Systemically, however, they have to be administered in such highdoses that steroid toxicity frequently occurs. After theirdiscontinuation severe relapses or even transformations into the chronicpustular forms can occur. Relapses also occur following topicalapplication of corticoids.

The folic-acid antagonist methotrexate is likewise regarded as effectiveantipsoriatic agent. Methotrexate is an effective agent with medium tosevere psoriasis-arthritis. On account of the high risk ofhepatotoxicity, myelotoxicity and gastrointestinal toxicity, themethotrexate treatment is, however, restricted to patients acutely illwith generalized severe forms of psoriasis. The compounds of thisapplication have a proliferation-inhibiting effect even with topicalapplication, with the result that apart from the systemic treatment ofpsoriasisarthritis they can also gain importance for the topicaltreatment of psoriatic skin abnormalities. Side-effects along the linesof those found with the antipsoriatic agents already on sale, are notanticipated with the substances according to the invention on the basisof their chemical properties.

Great importance must be placed on the development of lipophiliccytostatic agents, since the wellknown substances do not reach the CNSat all or reach the CNS only in therapeutically insufficientconcentrations, and thus a satisfactory cytostatic medication ofmalignant tumors of the CNS is currently not possible. The differenttypes of leukemia in particular come into consideration as an especiallyinteresting indication for a lipophilic cytostatic agent, since thesefrequently disseminate into the CNS, from whence the disease process isfurther sustained. Another potential advantage of a cytostatic agentwith lipophilic properties is the enrichment in particularly high-fattumors, which can therefore possibly be influenced preferably.

The following comparison trials verify the action of the compounds ofthe general formula I.

COMPARISON TRIALS I. Investigation for immunosuppressive activity in theskin graft survival test in rats

Substance A (4-amino-N(2'-aminophenyl)-benzamide) according to theinvention was tested on rats and rhesus monkeys for immunosuppressiveactivity in the skin grafting model; in the experiments on rats it wascompared with the international immunosuppressive standard azathioprineas well as with a combination medication generally used at present inorgan transplantations, consisting of high-dosage azathioprine andlow-dosage methylprednisolone. Substance A was at least equally aseffective as the comparison medication in these trials, although farsmaller substance quantities were used. In rhesus monkeys theimmunosuppressive action was also markedly clear. As demonstrated onthis species, the extension of the normal survival time of allogeneicskin grafts affected by substance A is characterized by the simultaneousdistinct reduction of the peripheral lymphocytes.

    ______________________________________                                        (A) Technique                                                                 ______________________________________                                        Comparison medication:                                                        Trial I/azathioprine + methylprednisolone                                     Trial lI/azathioprine                                                         Preparation:                                                                              As suspension freshly prepared                                                before each adminstration                                         Route of ad-                                                                              intragastric via stomach tube,                                    ministration:                                                                             suspended in 0.8% Methocel                                        Volume:     0.01 ml per gram body weight and                                              dose                                                              Dosage schedule:                                                              Trial I/from Day -3 before grafting to Day +6                                 Trial II/from Day -2 before grafting to Day +9                                Tested doses:                                                                 Trial I/10 mg/kg over 6 days, afterwards                                      5 mg/kg daily for 4 days                                                      Trial II/4-8 mg/kg daily increasing over                                      12 days                                                                       ______________________________________                                    

(B) Trial Design

Two allogeneic skin grafts from a donor rat are transferred to areceiving rat from an unrelated inbred strain. The panniculus carnosusattached to the graft may either be removed by dissection(suprapannicular graft) or be left on the graft (subpannicular graft).Grafting is conducted on Day 0 under light ether narcosis subsequent toshaving and cleanup of the grafting sites. The grafts are fixed on thegraft receptor sites by dressing with a suitable bandage. From Day +9 aprotective collar is placed on the animals, the bandage removed and thestatus of the grafts daily controlled. The assessment of the graftfunction is conducted by means of a graduation scale, which allows for adifferentation of rejection corresponding to a three-degree of severityscore. The trial ends on the day when 50% of the animals of one grouphave rejected both grafts. The lengthening of the graft survival time incomparison to the controls is determined in days.

(C) Results

As can be deduced from the following Table I and II, in Trial Isubstance A was superior to an immunosuppressive standard medicationcomprising azathioprine and methylprednisolone. In Trial II substance Awas equally as effective as the immunosuppressive standard azathioprine.Due to the high activity of substance A, however, far smaller quantitiesof the substance were necessary to achieve the action compared with thestandard medication.

Table I shows the results of Trial I, skin graft survival test, in rats.Recipient: Long Evans ♂, Donor: Lewis ♂ Two suprapannicular grafts weretransferred from a donor to a recipient.

Table II shows the results of Trial II, skin graft survival test, inrats. Recipient: Osborne Mendel ♂, Donor: Lewis ♂ Two suprapanniculargrafts were transferred from a donor to a recipient.

                                      TABLE I                                     __________________________________________________________________________    Animals with Two Rejected Grafts/n (%)                                        Test Substance                                                                Dosage    Day +9                                                                             Day +10                                                                            Day +11                                                                            Day +12                                                                            Day +13                                                                            Day +14                                                                            Day +15                                                                            Day +16                                                                            Day +17                     __________________________________________________________________________    Control   1/6(17)                                                                            3/6(50)*                                                                           4/6(66)                                                                            4/6(66)                                                                            4/6(66)                                                                            5/6(83)                                                                            6/6(100)                                                                           --   --                          Methocel i.g.                                                                 Substance A**                                                                           0/5(0)                                                                             0/5(0)                                                                             0/5(0)                                                                             0/5(0)                                                                             1/5(20)                                                                            1/5(20)                                                                            3/5(60)*                                                                           4/5(80)                                                                            5/5(100)                    10 mg/kg i.g.                                                                 from Day -3 to                                                                Day +2 afterwards                                                             5 mg/kg i.g. from                                                             Day +3 to Day +6                                                              Azathioprine                                                                            0/6(0)                                                                             0/6(0)                                                                             1/6(17)                                                                            2/6(33)                                                                            2/6(33)                                                                            4/6(66)*                                                                           6/6(100)                                                                           --   --                          40 mg/kg i.g. +                                                               methylprednisolone                                                            2 mg/kg i.g.                                                                  from Day -3 to                                                                Day -6                                                                        __________________________________________________________________________     *Day of rejection: at least 50% of the animals have rejected both grafts.     **Substance A: 4amino-N--(2aminophenyl)-benzamide (Example 1).           

                                      TABLE II                                    __________________________________________________________________________    Animals with Two Rejected Grafts/n (%)                                        Test Susbstance                                                               Dosage   Day +8                                                                             Day +9                                                                             Day +10                                                                            Day +11                                                                            Day +12                                          __________________________________________________________________________    Control  2/10(20)                                                                           5/10(50)*                                                                          6/10(60)                                                                           8/10(80)                                                                           9/10(90)                                         Methocel i.g.                                                                 Substance A**                                                                          0/10(0)                                                                            1/10(10)                                                                           1/10(10)                                                                           1/10(10)                                                                           6/10(60)*                                        4-8 mg/kg i.g.                                                                from Day -2 to                                                                Day +9                                                                        Azathioprine                                                                           0/10(0)                                                                            1/10(10)                                                                           2/10(20)                                                                           4/10(40)                                                                           5/10(50)*                                        20-60 mg/kg i.g.                                                              from Day -2 to                                                                Day +9                                                                        __________________________________________________________________________     *Day of rejection: at least 50% of the animals have rejected both grafts.     **Substance A: 4amino-N--(2aminophenyl)-benzamide (Example 1).           

II. Investigation of Substance A for immunosuppressive activity in theskin graft survival test in rhesus monkeys (Macaca mulatta)

The demonstration of the action in the skin grafting model is to beevaluated as evidence of an inhibition of the cellular immune system(T-lymphocytes), since this is decisively involved in the rejection ofallogeneic grafts according to the currently prevalent opinion.

An inhibition of the humoral immune system (antibody-producingB-lymphocytes) by the substances of the invention and a possibility oftherapy resulting from this, e.g. for autoaggression diseases, which arecharacterized by an increase in antibody production against the body'sown tissues, can currently only be concluded indirectly. An increasedsusceptibility to bacterial infections observed in rats treated over asustained period with high doses of substance A is to be regarded as anindirect demonstration of the inhibition of humoral immunoresistance.

    ______________________________________                                        (A) Technique                                                                 ______________________________________                                        Control standard:                                                                              Not used for ethical reasons                                 Preparation:     Freshly prepared before each                                                  administration                                               Route of ad-     Intragastric via stomach                                     ministration:    tube, suspended in 0.8%                                                       Methocel                                                     Dosage schedule  1 × daily for 10 days                                  Tested dose:     10 mg/kg                                                     ______________________________________                                    

(B) Trial Design

Altogether four allogeneic skin grafts from two different donor animalsare transferred crosswise to one unrelated receiving animal. At firstthe grafts are removed under ketamine narcosis from the shaven andcleaned stomach skin of the donor animals and freed of any fat attached.The four graft receptor sites are prepared on the shaven and cleanedback of the receiving animal under ketamine narcosis by removingsuitably-sized pieces of skin. Subsequent to successful hemostasis, thegrafts are spread out on the graft receptor sites and sewn to the edgesof the wound. The wound is covered with a suitable dressing material andthis is fixed with an elastic bandage. The bandage is opened on the 5th,7th, and 9th day after grafting and the function of the grafts examined.On the 9th day the bandage is no longer replaced. The graft function isthen controlled daily until rejection has occurred.

(C) Results

Controls are dispensed with in this trial on primates for ethicalreasons. Comparisons are drawn with the normal survival of allogeneicskin grafts or historic controls, stated as ten days. A lengthening ofthe normal graft survival time could be achieved with substance A in thetested dosage on test animal ZE by six to seven days, and by four tofive days on test animal YL. This result is to be interpreted as adistinct immunosuppressive action of the substance according to theinvention.

FIGS. 1 and 2 demonstrate the influence of a ten-day medication ofSubstance A on leukocytes and lymphocytes in the plasma of rhesusmonkeys.

Dosage: 1 X daily 10 mg/kg i.g.

FIG. 1: Rhesus monkey ZE, ♀

FIG. 2: Rhesus monkey YL, ♀

III. Investigation of the antineoplastic activity of Substance A onthree tumor models in mice

Upon intragastric administration of substance A to tumor-carrying mice,these demonstrated a significant increase in the average survival timeand a distinct retardation in the growth of the tumor concerned incomparison to the untreated control animals, according to the tumormodel used.

    ______________________________________                                        (A) Technique                                                                 ______________________________________                                        Preparation:     As suspension freshly pre-                                                    pared before each admin-                                                      istration                                                    Route of ad-     oral, suspended in 0.8%                                      ministration:    Methocel                                                     Volume:          0.01 per gram body weight                                                     and dose                                                     Dosage schedule  daily for 9 days, if not                                                      otherwise stated                                             Tested doses:    60, 120, 180, 240 mg/kg                                                       daily                                                        ______________________________________                                    

(B) Tumor Description

L 1210/Rij adaption of L1210 leukemia in CD₂ mice (C57B1×DBA2, F1hybride). On the day before administration of the substance 10⁵ leukemiccells are inoculated intraperitoneally. The cages are controlled 2×daily for dead animals. The terminal point is the mean survival of fivemice/dosage compared with ten untreated controls.

Osteosarcoma. C22LR in BCBA mice (C57B1×CBA/Rij, F1 hybride ). The tumoris subcutaneously inoculated bilaterally into the sides. It is measuredat least 2× weekly in three dimensions. The terminal point is theretardation of growth. It is defined as the difference of the averagetime in which the volume of five to ten tumors in five treated animalsreaches a given value in comparison with that of five to ten tumors inthe control animals. This value was determined as four times that of theaverage volume at commencement of treatment.

Lewis Lung Tumor in BCBA mice. The procedure is the same as withosteosarcoma. The volume of the tumor was determined here at 800 mm³(=product of the diameters in three dimensions).

(C) Results

Due to the toxicity of the selected dosages, daily applications were notpossible in most of the dosage groups. After mortality had occurred inall groups following two or more applications of 120 mg/kg or more, thenumber of administrations to the surviving animals was reduced. Thefindings can be seen in the following Tables III to V.

Assessment: The tested dosages were too high. In spite of this asignificant activity of the tested substance could be proved with L1210in a moderate dosage, a good activity with osteosarcoma and a moderateactivity with Lewis Lung Tumor.

The following Tables III to V reveal the results of the testing ofsubstance A on neoplastic activity in mice.

                  TABLE III                                                       ______________________________________                                        L1210                                                                                                      % Increase                                                        Mean Survival                                                                             in Mean                                          Dosage           Time (Days) Survival Time                                    ______________________________________                                        Controls    (n = 10) 8           --                                           Test groups:                                                                  9 × 60 mg/kg PO                                                                     (n = 5)  11          38%                                          7 × 120 mg/kg PO                                                                    (n = 5)  6           toxic death                                  4 × 180 mg/kg PO                                                                    (n = 5)  5           toxic death                                  4 × 240 mg/kg PO                                                                    (n = 5)  5           toxic death                                  ______________________________________                                    

                  TABLE IV                                                        ______________________________________                                        Osteosarcoma                                                                                              Retardation in                                                      Surviving Growth of Tumor                                   Dosage            Animals   (Days)                                            ______________________________________                                        Controls     (n = 5)  5/5       --                                            Test groups:                                                                  9 × 60 mg/kg ip                                                                      (n = 5)  5/5       7,8 (p = 0,0001)                              4 × 120 mg/kg PO                                                                     (n = 5)  0/5(Day 5)                                                                              toxic death                                   2 × 180 mg/kg PO                                                                     (n = 5)  1/5       9,6                                           1 × 240 mg/kg PO                                                                     (n = 5)  5/5       3,1 (p = 0,001                                ______________________________________                                    

                  TABLE V                                                         ______________________________________                                        Lewis Lung Tumor                                                                                          Retardation in                                                      Surviving Growth of Tumor                                   Dosage            Animals   (Days)                                            ______________________________________                                        Controls     (n = 5)  5/5       --                                            Test groups:                                                                  9 × 60 mg/kg ip                                                                      (n = 5)  5/5       3,8 (p = 0,061)                               4 × 120 mg/kg PO                                                                     (n = 5)  0/5       toxic death                                   2 × 108 mg/kg PO                                                                     (n = 5)  0/5       toxic death                                   1 × 240 mg/kg PO                                                                     (n = 5)  5/5       3,5 (p = 0,018)                               ______________________________________                                    

IV. Investigation of substance A for antiproliferative activity upontopical administration to rats

    ______________________________________                                        (A) Technique                                                                 ______________________________________                                        Control standard:                                                                             No control standard known                                     Preparation:    Fresh before each adminis-                                                    tration                                                       Route of ad-    Topically by pipetting as                                     ministration:   0.5% solution in absolute                                                     ethanol                                                       Volume:         1 ml per animal and dose                                      Tested dose:    5 mg/animal daily for 14 days                                                 10 mg/animal daily for 7 days                                 ______________________________________                                    

(B) Trial Design

A protective collar is placed on male rats of the long Evans strain, furcolor "blackhooded." A rectangle measuring 3 cm long and 1.5 cm wide ismarked with the aid of a template on the dorsal skin in the region ofthe black dorsal hair strip subsequent to shaving and cleansing. Thetest solution is slowly applied dropwise to this rectangle, so as toavoid it running off onto the surrounding skin. The solvent is appliedin the same manner to the control animals. After 21 days of treatmentthe hair growth is assessed on the treated areas compared with thecontrol areas.

(C) Results

A clear inhibition of hair growth can be seen with the treated animalsin comparison with the control animals.

Assessment: Although it cannot be excluded that part of the substanceadministered was involved in a systemic manner in the inhibition of thegrowing hair follicle due to a possible percutaneous resorption, itcould be demonstrated that a distinct antiproliferate action is achievedwith the substance of the invention on adnexes of the skin, upon topicalapplication.

V. Central Actions of Substance A

The penetrating ability of the substances of the invention into the CNSand other lipoid organs can also be demonstrated by their markedanticonvulsive effects in the maximal electroconvulsion test (Swinyardet al., J. Pharm. exp. Ther. 106, 319 (1952) and in thepentetrazoleconvulsion model (loc. cit.):

                  TABLE VI                                                        ______________________________________                                        Anticonvulsive Action of Substance A in Mice                                                Substance A Diphenylhydantoin                                                 ED.sub.50 mg/kg                                                                           ED.sub.50 mg/kg                                     Convulsion model                                                                            (i.g.)      (i.g.)                                              ______________________________________                                        Electro-convulsion                                                                          30.0 (21-42)                                                                              22.5 (18-28)                                        Pentetrazole- 44.0 (32-60)                                                                              9.5 (7-13)                                          convulsion                                                                    ______________________________________                                    

So as to make the magnitude of the central effects clear, the standardantiepileptic agent diphenylhydantoin was brought in as a referencesubstance.

The seven-day values of the acute, oral (i.g.) toxicity of substance Aand diphenylhydantoin in mice are listed comparatively in Table VII.

                  TABLE VII                                                       ______________________________________                                                        Confidence level in mg/kg                                              LD.sub.50          p = 0.05                                                   mg/kg    lower     upper                                             ______________________________________                                        Substance A                                                                              625        469.9     831.2                                         Diphenyl-  128        114.2     143.3                                         hydantoin                                                                     ______________________________________                                    

The following Examples are given for the purpose of illustrating theinvention:

EXAMPLE 1 4-Amino-N-(2'-aminophenyl)-benzamide

C₁₃ H₁₃ N₃ O MG 227.26

22.7 g o-Nitroaniline, dissolved in 130 ml anhydrous dioxane, are mixeddropwise with a solution of 30.4 g p-nitrobenzoylchloride in 150 ml drydioxane. The reaction is brought to a close by heating for one hourunder reflux. Upon cooling to 15° C. N-(2'-nitrophenyl)-4-nitrobenzamideis precipitated in crystalline form. After recrystallizing fromchlorobenzene 39 g (83% of theory) with a melting point of 217°-218° C.are obtained.

39 g of the dinitro-product are hydrated in 550 ml dimethylformamide inthe presence of 10 g Raney-Ni for one hour at 25° C. and a pressure ofabove 2 atmospheres.

It is filtered off from the catalyst, the solvent removed in a vacuumand the title product recrystallized from ethanol. Yield 20.2 g (66% oftheory) with a melting point of 180°-181° C.

Using a solution of HCl-gas in ethanol the compound can be converted todihydrochloride, which is 4% water soluble.

4-Amino-N-(2'aminophenyl)-benzamide-dihydrochloride

C₁₃ H₁₅ N₃ Cl₂ O MG 300.18, melting point 340° C. (from ethanol)

EXAMPLE 2 4-Methylamino-N-(2'-aminophenyl)-N-benzamide

2.71 g N-(2-Nitrophenyl)-4-methylamino-benzamide are dissolved in 300 mltetrahydrofuran and hydrated with Raney-Ni in a shaking apparatus. Thetemperature rises from 21° C. to 26° C. during hydration. Subsequent tofiltering off from the catalyst, the clear solution is evaporated andthe residue recrystallized from ethyl acetate.

There is obtained 1.3 g (56.5 % of theory) of4-Methylamino-N-(2'-aminophenyl)-N-benzamide, mp.189° C.

The N-(2-nitrophenyl)-4-methylamino-benzamide employed as startingproduct is prepared in the following manner:

4.535 g (0. 03 mol) 4-Methylamino-benzoic acid are heated while stirringwith 9.19 g (0.09 mol) acetic anhydride to 100° C. for one hour. Thecrystals precipitated out after cooling of the clear solution arefiltered off with suction and washed with ethyl acetate (mp. 199°-201°C.). The N-acetyl-4-methylamino-benzoic acid obtained (yield 62 %) isthen converted by means of thionylchloride in dioxane into the acidchloride. The excess of thionyl chloride is then stripped off with somedioxane in a water-jet vacuum. 2.76 g (0.02 mol) o-nitroaniline in 10 mldry dioxane are added dropwise to the reaction mixture and the solutionmixed with 4.04 g (0.04 mol) triethyl amine (as HCl-absorber). Thereaction mixture is then boiled under reflux for one hour. Theevaporated reaction residue is mixed with 40 ml of water and extractedwith methylene chloride. After evaporation of the organic phase, 4 mlisopropanol are added thereto and the crystals formed filtered off bysuction after previous stirring for 30 minutes.

There are obtained 5.1 gN-(2-Nitrophenyl)-4-N-acetyl-N-methyl)-amino-benzamide (mp. 162° C.) ina yield of 55.6 % of theory. The crude product thus obtained is thensuspended in a small amount of ethanol and hydrolyzed with theseven-fold molar amount of concentrated hydrochloric acid under refluxfor 9 hours. The reaction mixture is evaporated to dryness and broughtto crystallization by the addition of isopropanol, then dissolved in 40ml water and alkalized with ammonia. After extraction withmethylene-chloride there are obtained 1.4 gN-(2-nitrophenyl)-4-methylamino-benzamide with a mp. of 187° C. and in ayield of 51 % of theory.

The following compounds are obtained in an analogous manner:

4-amino-N-(2'-methylaminophenyl)-N-benzamide4-methylamino-N-(2'-methylaminophenyl)-N-benzamide EXAMPLE 34-Amino-N-(2'-aminophenyl)-N-methylbenzamide

22.82 g (0.15 mol) N-methyl-o-nitroaniline are dissolved in 70 ml drytetrahydrofuran and mixed dropwise with 30.6 g (0.165 mol)p-nitrobenzoyl chloride in 90 ml dry tetrahydrofuran while stirr ng andbubbling nitrogen through the reaction mixture. Stirring is thencontinued under reflux for two hours under an atmosphere of nitrogen.The reaction mixture obtained is concentrated and recrystallized fromacetyl acetate.

There are obtained 29.2 g (64.6 % of theory) ofN-methyl-N-(2-nitrophenyl)-4-nitrobenzamide with a flow point of137°-138° C., which is dissolved in 800 ml tetrahydrofuran and hydratedwith 10 g Raney-Ni in a shaking apparatus while applying cooling withwater. The temperature should not exceed an upper limit of 25° C. After7 hours, 10 g Raney-Ni are again added thereto and after further 6 hoursthe colorless solution evaporated to dryness, the residue dissolved inethyl acetate and precipitated with diisopropyl ether.

There are obtained 18 g of4-Amino-N-(2'-aminophenyl)-N-methyl-benzamide; mp. 159°-160° C.

The following compounds are obtained in an analogous manner:

4-methylamino-N-(2'-aminophenyl)-N-methylbenzamide4-methylamino-N-(2'-methylaminophenyl)-N-methylbenzamide4-amino-N-(2'-methylaminophenyl)-N-methylbenzamide

We claim:
 1. A compound of the formula ##STR6## wherein one of theradicals R⁴ and R⁵ represents methyl and the other hydrogen; R⁶ ishydrogen or methyl, or a pharmacologically acceptable acid addition saltthereof.
 2. A compound and being4-methylamino-N-(2'-aminophenyl)-benzamide.
 3. A compound and being4-amino-N-(2'-methylaminophenyl)-benzamide.